Friday, August 14, 2015

Elbowing my Way Back

I have been quiet on the blogging front for a while now, and not for any lack of things to say. Maybe more it has been part of the break I have been taking to rest my elbow after the PRP procedure I underwent about 8 weeks ago. The climb back out of the sandpit has been a long and slow one, but in the past week I feel like I have turned a corner and am starting to actually get better. This has been an uplifting situation and I am back, slowly and carefully, to working in the shop. There had been moments in the past few months where I really was wondering if I would ever recover, and whether I might have to look for another path of work. Glad to have dodged that bullet.

It's amazing how much damage to a few square mm on your body can really put a crimp in what you do. Added to the mindfulness of the work itself, is the mindfulness about how I use my left hand in every move - - how I pick up a piece of wood, how I hold a tool, how I pull on something. A moment of inattention and you can set things back in a blink.

I'm thinking that moving forward I need to find ways to reduce the amount of time swinging a mallet as a means of reducing the loading on my outer elbow. I need to do less chopping. So, to that end I have a few ideas and we'll see what develops. I doubt I'll be pounding out mortises too often in the future. I need to find other ways to do the grunt work in that regard.

During the interim I've been spending a lot of time in my garden, and it has been a good summer in that regard. Always good to have ones hands in the dirt - though I have been avoiding using a shovel altogether.

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I've also been shopping for shop equipment, and have some news in that regard. For a while now I have recognized how useful a universal milling machine could be to my work. Problem is, Bridgeport-type milling machines are intended expressly for use on metal, and therefore operate spindles on lower rpms than would be suitable for woodworking. I know some people do use Bridgeports to do some woodwork, and appear to manage okay, but those machines really aren't ideally configured for woodworking. And given that my working of materials other than wood remains but a tiny fraction of what I do, it hasn't made sense to obtain a Bridgeport, even one with a 'high speed' head.

However, it turns out there is a type of universal milling machine which is meant for working wood, known as patternmaker's milling machines. I first saw one of these down on Alameda island in San Francisco at a shop on an old air base, an enormous Oliver. Here's a picture of an early Oliver with a giant amount of 'x' travel:


There was one of these for sale on Ebay in the past year, and the price, IIRC, was north of $10,000. I had an Oliver jointer a few years back, and I wasn't impressed with the build quality, so an Oliver patternmaker's milling machine was not exactly beckoning.

The Oliver was, by all accounts, based on a machine built by Wadkin - in fact, Oliver was licensed to sell Wadkin milling machines in the first decade or two of the 20th century, according to this account.

Wadkin's machine looked like this:



According to Wadkin's site, the company was originally formed for the purpose of making pattern milling machines, in 1897. There certainly aren't many of these machines around today, and in the past couple of years I do not recall seeing any on the market, though I haven't been looking specifically for one.

What I have been looking at specifically is a German-built pattern milling machine, by the company Zimmermann. They made a number of models from tiny machines using the equivalent of a trim router as the spindle drive, to much larger machines. Their largest, latest and greatest machine of this type was the FZ-5V Unimill:



It can be hard to get a sense of scale from a picture like that, so perhaps this photo will be more helpful:


The picture on the left shows a version of the machine with a tracer, so these could be set up as a tracer mill if so desired. The main spindle head is shown on the right-side portion of the picture.

I've long admired Zimmermann machinery- I would be happy having one of everything they make - though that is likely to remain an unfulfilled fantasy at best. For the past couple of years there has been an intriguing version of the Unimill, the FZ-5V, for sale, and I had been keeping an eye on it. Like the tracer mill variant, there are two spindles, however on this FZ-5V the secondary spindle is a high speed spindle, capable of 14,000 rpm. Here's a look at that machine, built in 1971:


The main spindle at front has 16 speeds, going from 56rpm to 4500 rpm. The high speed rear spindle operates at two speeds, 14,000 being the top. From the floor to the top of the main spindle head is about 94" (240cm), and the machine weighs north of 2 tons. Like a lot of quality machinery, the main table is planed and the ways are all scraped. The table is powered on the x and z axes, and also rotates. There is a digital readout, a later add-on and hardly a factory-quality install with the plywood support.

Another view:


That machine was for sale, but it's no longer on the market - - because I just bought it! It is going to be the oldest machine in my shop.

I'd been watching the machine for a couple of years - no serious buyers appeared, so I was lucky - and just last week I sold my Landcruiser truck. I decided I would rather put the money into a nice machine than another automotive money pit. I think this machine will outlast pretty much any vehicle I could buy, and will help me make a bunch of stuff as well. What's wrong with that?

There is no parts support from Zimmermann, however the machine is quite complete and heck, you can even use the machine to make it's own repair parts.

A lot of pattern making in Germany involves milling foam, and I have often come across foam cutters for these mills. I'm hoping that the mill i have purchased spent a lot of time milling foam, as that would mean less wear and tear to be sure. I asked the sellers, Fritz Ernst, to take a couple of videos, one showing that everything worked, and another with a dial indicator showing spindle run out. Run out was very minimal.

This machine runs on 3-phase 380v. 50hz. service, and of course I do not have such service in my shop. I considered at first seeing if the motors could be swapped out for ones which run on my shops supply of 3-phase 208v. 60hz., however only two of the motors could be swapped out. I'm sure with some craft machining, other solutions could be found in that regard however.

Doing more research, it turns out that a critical aspect to motor electrical supply is the design ratio between voltage and frequency for the motors.

380 (volts), divided by 50 (hertz) gives a ratio of 7.6:1

If you have 60hz. supply, and multiply 60 by 7.6, you obtain 454 (volts). So, a supply of 454v/60hz. will be in the same voltage:frequency ratio as 380v/50hz. The main difference will be that of the frequency difference, 60/50 - or 1.2:1, which means that a 50hz. motor run on 60hz. will spin 20% faster. This also means that the motor fan spins 20% faster, so the cooling increases as well. As the machine has no electronics or computer timers, etc., items sensitive to changes of frequency, it should be fine running at 454/60.

I went to look at a Zimmermann lathe in Boston a couple of years back, and the machinery dealer was running that machine, a 380/50 model, on 460/60 just fine, so I feel confident about using a different input voltage and frequency.

As far as a milling machine for wood goes, higher speeds are all good as far as I'm concerned. this means that the total speed range for this machine will be 56x1.2 = 67.2rpm to 14,000x1.2 = 16,800 rpm. The machine is built, according to the manufacturer's brochure, to mill steel and iron as well as other materials. It should prove to be quite versatile.

I need only obtain a step-up transformer converting my 208v. supply to 454v. and I have ordered one from a company in Montreal. I'll need a few other electrical bits of course.

Taking the plunge with the Unimill means I have also obtained a drill press in the bargain, so that enabled me to sell the Delta rockwell radial ram drill press a few weeks back. It had spindle run-out and no parts support - Delta is a crappy company these days - and I was glad to get rid of it. I sold it as a parts machine to a guy in Rhode island who was rebuilding one.

Intending to finish that series I had started on Pittsburgh architecture, along with a new post in the sideboard series, so look for those soon.

All for now, over and out. Thanks for coming by!

12 comments:

  1. Higher motor speeds can cause problems with fans and pumps, where power consumed varies with speed to the power 5! Power consumed by fans and pumps more than doubles. But modern electronic VVF (variable voltage and frequency) motor drives are no longer expensive and offer the option of soft motor start and infinite speed control too...

    ReplyDelete
    Replies
    1. Thanks for the comment Bandit.

      Quoting directly from 50hz60hz.com,

      "Since motors are constant torque machines then by applying the formula that HP = (torque*RPM)/5252 then you can see that with a 20% increase in speed the motor would also then be able to produce 20% more horsepower. The motor would be able to produce rated torque at both frequencies only apply if the V/Hz ratio is constant, meaning that at 50 Hz the supply voltage would need to be 380V and at 60 Hz the supply voltage would need to be 460V. In both cases the V/Hz ratio is 7.6 V/Hz.

      A potential solution for this problem would be to apply a variable frequency drive in this application which would be able to take in the 460V/60 Hz power source and output 380V/50Hz to the motor, putting everything back to the original design."

      I am contemplating the addition of a VFD to the system, however
      I'm suspecting that it may not be necessary. Other anecdotal accounts out there would seem to confirm this. Unlike a pump or fan, the motors on this machine do not operate on anything like a continuous basis, more like a few minutes here and there.

      ~C

      Delete
  2. Glad to hear you are recovering. I had trouble after a supposedly minor carpal tunnel surgery about 5? years ago. Months after the surgery I could not even hold a pencil and it was frightening to think of my woodworking future, so I know how you felt.
    Your new machine looks wonderful and I hope it works out for you. I do like the old Wadkin, how cool for so long ago!

    ReplyDelete
    Replies
    1. Julie,

      comment much appreciated. Injuries can be a little scary, more so when they are slow to heal. Part of it, in my case, is my 50 year old body doesn't heal nearly as fast as when I was younger.

      ~C

      Delete
  3. Chris;
    Glad to here you are getting better! How are your wood in the garden holding up? Machine looks like it could be really helpful. Thanx for all, drive safe!
    J.T.

    ReplyDelete
    Replies
    1. JT,

      thanks for the comment. Your question reminded me that I was planning to post an update on the topic of wood in my garden, so thanks for that.

      ~C

      Delete
  4. I'm a big fan of VFDs for meeting industrial motor requirements. I've used them on metal lathes, air compressors and a Fray milling machine (much like a Bridgeport). What sort of rust preventative and lubricating oils do you use on the large equipment? I would think that staining the wood is a concern.

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    Replies
    1. Anton,

      thanks for the input. I'm strongly considering a 3-phase vfd however getting useful information from the companies online that sell them can be challenging. It looks like a vfd for 10 hp will run around $800.

      There are any number of products out there which can be used on metal surfaces to prevent rusting which do not stain wood, Waxlit being an common one.

      ~C

      Delete
  5. Hi Chris, sorry to hear of your injury, we are truly fragile creatures. On a more positive note, there are really great machines to do your mortising for you...
    Peace,
    Harlan B.

    ReplyDelete
    Replies
    1. Harlan,

      thanks for your comment. Having a week off in upstate New York presently, which is giving me an opportunity to rest some more.

      There are certainly many options for mortising, and I've got the hollow chisel and drill press covered it would seem. So that's a start.

      ~C

      Delete
  6. Chris great to hear your elbow healed. My hammer swing elbow....left arm was bad...sore for almost a year or two...several years back after driving roofing nails for cement siding...by hand!!!! I thought the pain would never get better but its healed and good as new now.

    Ward

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    Replies
    1. Ward,

      well, not completely healed yet, but 90% back I would guess. My ortho guy said that I need to be careful in this phase of the healing not to go too hard too fast. Good to hear you managed to heal from your elbow troubles.

      ~C

      Delete

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